如何为 Char 数组赋值？

Question

Say I have the variable:

Var question : array[1..50] of char;

When I do:

question := 't'; //What is the correct way to change the value?

It returns an error:

Incompatible types: 'array[1..50] of Char' and 'Char'

Note: I want to have a max string size of 50 chars, not 50 different chars.

The reason for this question is that I have a record in another unit(This is just a basic example, not what I actually have written above) In that unit I have a Record, which I can't use the string data type in(Or is there a way? please explain if there is). I just need to know how to give an array of chars a value.

Answer 1

While Delphi strings and arrays of char are related, they are not the same.

Delphi overloads assignment of strings and literals (char and string) to array of chars, but only when the lower array bound is zero.

The following code works for me in D2007 and Delphi XE:

  var x : array[0..49] of char;
  begin
    x:='b';  // char literal
    x:='bb';  // string literal      
  end.

If I change the [0 to [1 it fails. This limitation probably simplifies the language helper that takes care of this, and probably the feature is only meant for dealing with converted C structs where arrays always have lower bound 0.

Answer 2

Are you sure that you can't use string data type in a record? Anyways...

type
  TCharArray = array[Char] of Char;

function StringToArray(Str: string): TCharArray;
begin
  FillChar(Result, High(Byte), #0);
  Move(Str[1], Result, length(Str));
end;

procedure TestCharArray;
var
  question: TCharArray;
begin
  question := StringToArray('123');
  ShowMessage(PChar(@question));
end;

Also take a look at StrPCopy function.

Answer 3

If you don't need unicode characters, you should just define your string like string[50] .

After that you don't need any functions or conversions to work with that string, and it'll be just as easy to read and write it to a file.

Hscores = record
var
  _topscore : integer;
  _topname : string[50];
end;  

Answer 4

I'm pretty sure you can use strings in record types.

This blog entry shows an example: http://delphi.about.com/od/beginners/a/record_type.htm

In order to assign a value to the Char array, you have to index it, like any other array:

question[1] := 't';